This invention relates to a safety device for a pressure vessel in which a frangible member or diaphragm prevents undue pressure buildup in the vessel and is visible through a protective cap.
A safety device of the general type contemplated by this invention is a releif device adapted to be secured around an opening in a pressure vessel such as that used on railway tank cars, tank trucks, tank barges and stationary tanks in refineries and storage areas. The safety device includes an opening in the pressure vessel leading to the atmosphere which is closed by a frangible member adapted to rupture at a predetermined pressure. In prior art devices, this frangible member is hidden from view and may rupture without being readily apparent to inspection personnel.
Patents that disclose safety devices of the type contemplated by the subject invention are the Smith, et al. U.S. Pat. No. 2,536,321, the Folmsbee, et al. U.S. Pat. No. 3,310,197, the Carlson U.S. Pat. No. 3,845,878, the Fryer U.S. Pat. No. 1,157,685 and the Martin, et al U.S. Pat. No. 3,238,574.
Additional prior art patents enclosed herewith relate to sight glass assemblies providing visibility of the interior of a vessel and are illustrated by the Meginnis U.S. Pat. No. 3,625,390, the Lewis U.S. Pat. No. 1,179,441, and the Farr U.S. Pat. No. 3,199,488.